Process for reproducing images



Patented Aug. 23, 1938 UNITED STATES PATENT OFFICE PROCESS FORBEPBODUCING IMAGES No Drawing. Application June 13, 1936, Serial Pie.85,053

3Claima.

This invention relates to a novel and improved method of faithfullyreproducing images upon solid surfaces. More particularly, it relates toa process for reproducing a decorative finish upon a hard, planesurface, such, for example, as a sheet metal panel.

Heretofore, the process most satisfactory and most successful from acommercial standpoint for reproducing images upon plane surfaces hasembodied substantially the features disclosed in U. 8. Patent No.1,548,465 to Henry. In accordance with the teachings of this patent,which is primarily directed to the reproduction of wood grain on sheetmetal panels, a suitable section of wood is photographed in the usualmanner to produce a negative photographic plate. Subsequently, aphotographic positive is produced from this plate and a printing plateor roll is reproduced from the positive in accordance with practice wellknown in the photcgravure art. Preferably, the printing plate thusreproduced is formed by means of the well known Rembrandt screen inorder that the resultant product will have in its surface a plurality ofrecesses of varying magnitude. The plate is coated with a stain and adoctor blade or wiper is utilized for the purpose of removing surplusstain from the surface of the plate. When a soft roll is passed over theplate the masses of pigment or stain within the recesses will be pickedup on the roll and will be transferred to the surface upon which it isdesired to reproduce the image photographed. This process results in thesmall individual masses of pigment being merged and all lines of unionbetween the masses obliterated in order that a more detailedreproduction and a more uniform and attractive finish will be obtained.

The present invention contemplates the provision of a process whichobtains greatly improved results and which results in a reproductionmore faithful in detail than any heretofore obtainable. Further, it willbe appreciated that the process of the present invention is considerablysimpler than the Henry process outlined above and that the unnecessaryand undesirable steps forming an essential part of the Henry processhave been eliminated.

While it will be appreciated from the following detailed descriptionthat the process forming the basis of the present invention is primarilydirected to a method of reproducing a finish in imitation of naturalwood greining upon a sheet metal panel, the generic inventive conceptpresented herein is of much broader scope. It will be readily apparentthat certain features of the present invention and steps of the methodoutlined herein will iind great practical utility in any process whereinit is desired to reproduce upon a plane, hard or solid surface an imageof anything capable of being photographed.

In order that a full and complete understanding of the present inventionmay be obtained, the specific process outlined below is directed to thereproduction of an imitation wood grain finish on a sheet metal panel.The process may successfully be practiced in the following manner.

A photographic plate is first exposed to white light of uniformintensity and ordinary charactor for a period of relatively shortduration, the period, however, being sumciently long so that in theevent the plate were developed, the resultant product would berelatively dark and of uniform density throughout its entire surface.The particular length of this initial exposure depends upon manyvariable factors, for example, the particular type of photographicemulsion used on the plate, the nature and intensity of the source ofwhite light to which it is exposed, and the length of such exposure.

By way of illustration, the following initial exposure has been foundparticularly satisfactory and in the practice of the method of thepresent invention when conventional photographic plates now commerciallyobtainable are used. The plate is exposed for approximately two secondsto a 25-watt Opal tungsten lamp at a distance of eight feet. This plateis not developed after this initial exposure, but is subjected to adesensitizing process which materially reduces the speed or lightSBHSIUVEHESLL of the emulsion which covers the plate. While many andvarious methods may be utilized to obtain the necessary densltization ofthe exposed plate, the following process has been ,found particularlysatisfactory for accomplishing this purpose. The plate is preferablydesensitized by bathing it for three minutes in a desensitizing solutionwhich preferably is composed of:

The plate is preferably swabbed with cotton so that the wetting actionof the solution will be uniformly distributed over the entire surface ofthe plate. and while wet the plate is placed in a plate holder of acamera.

A section of wood has the surface thereof finished and prepared in amanner to bring out not only the grain of the wood in detail, but thehighlights and other ornamental effects thereof. A particuiariysatisfactory manner of accomplishing this is to utilize a filler ofChinese blue or Milori blue which may be worked into the surface of thewood in order to accentuate the ornamental appearance thereof.

While the particular manner in which the wood is photographed may bevaried within relatively wide limits, depending upon the specific typeof equipment used, it has been found particularly satisfactory to use acamera having a diaphragm opening of F22 and provided with a red colorfilter, preferably such as is known as a "Wrattan A 25 red" filter. Thecamera is focused on the sectin of wood which has been prepared asdescribed above for a period of approximately forty minutes with strongillumination. Manifestly, the length of the exposure is directlydependent upon the illumination and consequently the length of thisexposure may be varied within relatively wide limits. While varioustypes of cameras may be satisfactorily used for the purpose, it has beenfound particularly satisfactory to use a camera provided with aneighteen inch process lens and dispose the slab of prepared wood aboutthirty-six inches away.

After exposure, the plate is developed in the usual manner, then fixed,washed and dried, and the resulting product provides a positive image ofthe section of wood photographed, and it has been found that the imageupon the plate is particu larly clear, accurate and detailed. Further,it has been found that the minute features of the grain, the highlightsand other factors which contribute to the ornamental appearance offinished wood, are faithfully reproduced in detail.

After completion of the preparation of the plate in accordance -with themethod outlined above, any suitable process may be utilized for thepurpose of providing a printing roll or plate to be utilized fortransferring the image thus formed to solid surfaces. While any suitableprocess such as a half tone may be used for producing the printing plateor roll from the positive plate, it has been found preferable as willhereinafter be more clearly seen to utilize a photogravure process, suchfor example as .he following:

A print may be made from the plate on sensitized photo carbon tissuesuch as is ordinarily employed in the intaglio process of printing.After exposure in making the print on the carbon tissue, the latter isagain exposed to light. through a screen of the Rembrandt type in orderto break up the surface of the image into a plurality of individuallyisolated elements or bodies. This image is then etched upon a metallicplate in the conventional manner and the individual bodies making up theimage will be reproduced as recesses of a magnitude varying inaccordance with the darkness of the original plate for which themetallic reproduction plate was prepared.

' When paint, stain or pigment is applied to the metallic reproductionplate, the recesses will be filled and the surplus pigment may be wiped0d. The pigment disposed in these recesses may be transferred to thesurface upon which it is desired to reproduce the image by means of asoft resilient roll, which serves to merge the individual masses ofpigment and consequently obliterate all lines of union therebetween.providing. a faithful reproduction of the image photographed.

While t has long been well recognized that exposure of a plate to lightwill give a negative with certain emulsions, it has been found that uponfurther exposure a positive will result. These regression phenomena arenot fully understood. What is known as the Herschel effect is 'an evenmorepronounced regression phenomenon than the above, and it is thislatter effect which contributes materially to the present invention.

It has been found that if a photographic plate is initially exposed to asource of light and subsequently exposed to light of predominantlylonger wave length, this second exposure tends to act in a way whichserves to restore the emulsion substantially to its original conditionprior to initial exposure. As a result of experiments it has been prettydefinitely ascertained that this bleaching eflect is considerably morepronounced if the diflerence in wave length between the two exposures isrelatively great. Consequently, it may be appreciated that in the eventthat the wave length of the light used for the initial exposure issufficiently short the subsequent exposure may be made with ordinarylight, and the necessary regression phenomena will still be present.

It will be apparent from the foregoing that the plate, after its initialexposure. if developed in the conventional manner, would be uniformlydark throughout its entire surface. The process of photographing thedesired image through a red filter serves to exercise a bleaching effectupon those particular portions of the plate upon which the most light isprojected, consequently resulting in the direct production of agpositivePlate as a result of the photographing The particular dyes or pigmentedmaterials utilized for accentuating the grain of the wood should be ofsuch a color that they will not serve to reflect any appreciable amountof light upon the plate during the photographing process. The reasonthat Chinese or Milori blues are chosen for use in the foregoingspecific illustration of the process is that these two have been foundto be notably lacking in any red components and are hence extremelysatisfactory when a red filter is used.

It has been found that the image reproduced by the above donned processis, as has been pointed out, particularly faithful in detail. When thespecific process is utilized for the reproduction of wood graining onmetallic surfaces,as has been described above, the process results inthe clear and faithful reproduction of not only the grain structure butthe high lights of the wood grain, which features greatly improve theappearance of the resultantproduct.

It will be appreciated that the process outlined above may beconveniently utilized for the pur-.

pose of photographically reproducing almost any type of image upon aplane, solid surface and that the inventive concept is not limited tothe specific process of reproducing wood graining as outlined.

Many other and further modifications of the process outlined herein.falling within the scope of the invention as defined in the subjoinedclaims, will be clearly apparentto those skilled in the art.

I claim as my invention:

1. Themethod of reproducing wood graining upon a solid surface whichcomprises preparing a .wood panel to accentuate the grain thereof.initially exposing a photographic plate to a source of white light ofuniform intensity, partially desensitizing said exposed plate,phoiographlni said prepared wood panel through a color filter on saidplate to produce a positive reproduction oi the grain oi the woodthereon, said color filter serving to exclude light of short wave lengthand subsequently utilizing a photogravure process for reproducing theimage from said plate upon a solid surface.

2. The process of reproducing wood graining upon a solid surface whichcomprises initially exposing a photographic plate to a source of whitelight, subsequently partially desensitizlng said exposed plate,preparing a wood panel with blue dye to accentuate the grain thereof,photographing said prepared wood panel on said exposed partiallydesensitized plate through a color filter to produce thereon a positiveimage of the food grainlng in said panel, said color filter being of thetype which serves to excludes light of light, developing said plate,preparing a photogravure plate from said plate, and transferring theimage from said photogravure plate to a solid surface by a photogravureprocess.

ROBERT R. TANNER.

CERTIFICATE OF CORRECTION.

Patent No. 2,l2"( ,9l. l

August 25, 1958.

ROBERT R TAN'NER it is hereby certified that error appears in theprinted specification of the above numbered patent requiring correctionas follows: Page 5, first column, line 17, claim 2, for the word "food"read wood; and line 18, for "excludes" read exclude; and that the saidLetters Patent shouldbe read with this correction therein that the samemay conform to the record of the case in the Patent Office.

Signed and sealed this 11th day of October, A. D. 1958.

(Seal) Henry Van Aradale Acting comrhissioner of Patents.

said prepared wood panel through a color filter on said plate to producea positive reproduction oi the grain oi the wood thereon, said colorfilter serving to exclude light of short wave length and subsequentlyutilizing a photogravure process for reproducing the image from saidplate upon a solid surface.

2. The process of reproducing wood graining upon a solid surface whichcomprises initially exposing a photographic plate to a source of whitelight, subsequently partially desensitizlng said exposed plate,preparing a wood panel with blue dye to accentuate the grain thereof,photographing said prepared wood panel on said exposed partiallydesensitized plate through a color filter to produce thereon a positiveimage of the food grainlng in said panel, said color filter being of thetype which serves to excludes light of light, developing said plate,preparing a photogravure plate from said plate, and transferring theimage from said photogravure plate to a solid surface by a photogravureprocess.

ROBERT R. TANNER.

CERTIFICATE OF CORRECTION.

Patent No. 2,l2"( ,9l. l

August 25, 1958.

ROBERT R TAN'NER it is hereby certified that error appears in theprinted specification of the above numbered patent requiring correctionas follows: Page 5, first column, line 17, claim 2, for the word "food"read wood; and line 18, for "excludes" read exclude; and that the saidLetters Patent shouldbe read with this correction therein that the samemay conform to the record of the case in the Patent Office.

Signed and sealed this 11th day of October, A. D. 1958.

(Seal) Henry Van Aradale Acting comrhissioner of Patents.

